A Model for Prediction of Probability of Developing an Adverse Physiological Symptom in Individuals Percutaneously Exposed to VX Nerve Agent

A model is developed for the probability of toxic effects resulting from either vapour or liquid acute exposure of the skin to the organophosphonate nerve agent VX (O-ethyl S-2-diisopropylaminoethylmethyl phosphonothiolate), for which considerable relevant human toxicity information is available. This model focuses solely on percutaneous toxicity and incorporates population variability of response and variable permeability of the different regions of the body to the agent. An ECt50 value for nausea and vomiting due to whole body vapour VX exposure (neglecting respiratory contribution) is derived and compared with other estimated values. In addition, the model predicts the ED50 for liquid VX applied to various body regions, with a variation of about a factor of 300 predicted between the least and most sensitive body regions for which data are available. The predictions of the model appear consistent with available human effects data, and thus the effective dose predictions of the model are to be preferred over the somewhat less conservative estimates in the literature. The original document contains color images. Pub. in Jnl of Medical Chemical, Biological and Radiological Defense, v3, p1-22, 2005.